Apparatus for slitting an electron microscopy tissue embedding capsule casing

ABSTRACT

A capsule case slitting device receives an embedded electron microscopy tissue capsule and forces the capsule with its case between oppositely spaced blades to impart longitudinal slits in the capsule case thereby enabling the embedded tissue specimen to be easily separated from its casing.

0 United States Patent [191 [111 3,733,950 Kinney et al. 1 May 22, 1973[54] APPARATUS FOR SLITTING AN [56] References Cited ELECTRON MICROSCOPYTISSUE UNITED STATES PATENTS EMBEDDING CAPSULE CASING Inventors: ThomasD. Kinney, 3130 Devon 1,366,082 1/1921 Knabe ..83/924 X Road Durham NC27707 John 1,740,472 12/1929 McFarland ..83/425.3 E P Pickett 3 Pinaforebrive 2,880,636 4/1959 Freedman et a1, ..83/924 X Durham, NC. 27705 IPrimary Examiner-Frank T. Yost [22] Filed. Mar. 6, 1972 B Olive [21]App1.No.: 231,972

[57] ABSTRACT [52] [1.8. Ci. ..83/425.3, 83/437, 83/444, A capsule caseSmting device receives an embedded 83/924 electron microscopy tissuecapsule and forces the cap- E2 sule with its case between oppositelyspaced blades to 444 impart longitudinal slits in the capsule casethereby enabling the embedded tissue specimen to be easily separatedfrom its casing.

2 Claims, 6 Drawing Figures I APPARATUS FOR SLITTING AN ELECTRONMICROSCOPY TISSUE EMBEDDING CAPSULE CASING BACKGROUND OF THEINVENTION 1. Field of the Invention The invention relates broadly todevices for removing molded items from their mold and specifically todevices adapted to effect the removal of an embedded electron microscopytissue specimen from a surround- 1Q jects and advantages will appear inthe description and ing plastic casing mold by slitting the wall of thecasing.

2. Description of the Prior Art In the art of electron microscopy minutesamples of tissue which are to be examined must first be processed invarious dehydrants, stains and fixatives, then embedded in a plasticmaterial, then thinly cut into sheets on a rotary ultramicrotome, andfinally placed in a grid slot for viewing under an electron microscope.A convenient means for embedding the processed tissue has been theso-called Beem capsule which comprises a frusto-conically shapedpolyethylene casing measuring about 1.5 X 3.0 cm. at its larger end, andhaving an opening in the larger end to permit the insertion of thetissue to be examined and a fluid plastic embedding material whichhardens under appropriate conditions.

Before the fluid plastic has hardened, the tissue particle is requiredto settle to the bottom narrow tip portion of the capsule. Oncehardened, it is necessary to remove the embedded plastic block from itscasing preparatory to cutting the tissue on an ultramicrotome.Heretofore, a common practice for removing the block from the casing hasbeen for a technician to hold the capsule in his hand and make severallongitudinal slits in the capsule casing with a razor blade, surgicalknife or the like. The wall of the casing is divided at the slits andthe plastic tissue containing block is then removed. Typically, largenumbers of such capsules are processed daily in an active histologylaboratory and since the capsules are small and relatively difficult togrip, they tend to slip from time to time, often causing the blade to bediverted into the holders fingers. Thus, this method is both timeconsuming and hazardous.

An alternate means for enabling a tissue embedding to be removed from anembedding capsule is the wellknown Beem capsule press. This devicecomprises a movable arm situated above a platform having a circularaperture with a diameter corresponding to the embedded block diameterwhich is the same as the inside diameter of the Beem capsule casing. Anembedded capsule is placed open end down on the platform and above theaperture, and the arm is forced down upon the small tip of the capsule.The embedded plastic block, being of smaller diameter than the insidediameter of the capsule casing, is squeezed through the aperture, whilethe capsule casing is retained above. While this apparatus and techniqueare successful in removing the block from the capsule casing, it isreadily apparent that harm to the tissue specimen situated in the tip ofthe capsule may occur due to the impact and compression of the arm beingforced down upon the narrow tip. The resultant compression of the tissuespecimen might therefore ruin many hours work and cause irreplaceableloss in cases wherein like tissue specimens are no longer available.

In this respect, the prior art has not taught an adequate device forremoval of the embedded plastic tissue block from the capsule casingwithout causing possible appended claims which follow.

SUMMARY OF THE INVENTION The apparatus of the invention comprises a baseplate which can be mounted on a laboratory worktable, desk or the like.The base plate supports a guide member, a push rod assembly and acamming assembly. The guide member has a cylindrical receptacle intowhich a filled Beem type capsule is dropped. The push rod assemblyincludes a push rod which is designed to engage the open or filling endof the capsule and force the capsule past a pair of fixed razor bladeswhich slit both sides of the capsule casing. The camming assemblyincludes a handle and a cam arranged so that when the handle is turnedthe cam forces the push rod against the capsule to effect slitting ofthe capsule casing.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an apparatusconstructed according to the invention.

FIG. 2 is a side view of the invention apparatus showing the push rodlever and bearing assemblyv FIG. 3 is a top plan view of the inventionapparatus show-ing the capsule aperture.

FIG. 4 is a partial cutaway top view of the invention apparatus showingthe push rod in the closed position.

FIG. 5 shows the sequence in two positions of :a Beem type embeddingcapsule prior to and after slitting.

FIG. 6 is a perspective view of a typical single edge, rectangularshaped razor blade suited to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, theapparatus of the preferred embodiment generally designated 10, comprisesa base member 15, vertical support members 16, 17, slitter assembly 20and camming assembly 30. Slitterassembly 20, best shown in FIG. 4,includes guide member 21 having a central elongated cylindrical cavity23 extend ing the length of guide member 21, a pair of laterallydisposed elongated cylindrical cavities 24, 25 each having an open endand extending only part way the length of guide member 21, push rodmechanism 26 and blades 27, 28. Referring now to FIG. 3, guide member 21includes a rearward portion 12 and a forward tapering portion 14,tapering to a blunt end 13. An 'elongated opening 11, having a beveledtop peripheral edge 18, is centrally disposed in tapering portion 14 andopens into central cylindrical cavity 23-from above. Referring to FIG. 2horizontal slots .19 formed along the opposite tapered edges of taperingportion 14 are adapted to permit insertion of suitable single edge typerazor blades 27, 28, FIG. 6, so as to allow a corner end portion of eachblade to extend into the mentioned central elongated cavity 23.Appropriate set screws 35, 36, 37, 38, 39 and 40, shown in FIG. 1, areadapted to adjustably secure blades 27, 28 within slots 19. A feature ofnote is that blades 27, 28 are recessed in slots 19 so as to render theminaccessible to the user during normal operation thus eliminating thedanger of accidental bodily injury.

Referring now to FIG. 4, push rod mechanism 26 comprises a plate member55 to which are integrally secured a central push rod 50 and a pair oflaterally spaced guide rods 41, 42 having a slightly smaller diameterthan push rod 50. Rods 41, 42 are secured in an abutting relation andare rigidly secured to plate member 55 and each receives a coil spring45. Push rod 50 extends through plate member 55 to which it is rigidlysecured and has a slotted end 51 which receives pin 52 and roller 53.Rods 50, 41 and 42 are positioned in alignment with and axially movablewithin the respective cylindrical cavities 23, 24, 25. Springs 45 areadapted to reside within the respective cylindrical cavities 24, 25 andto surround rods 41, 42. Spring 45 thus causes the push rod mechanism 26to assume a normally open position, shown in FIGS. 1, 2 and 3, untilmechanism 26 is moved inwardly into guide member 20 and springs 45compressed, as shown in FIG. 4. Upon release, springs 45 then urgemechanism 26 back into the open position.

Camming assembly 30, best shown in FIGS. 2 and 3, comprises a cam 31secured to shaft 32 which is journaled for rotation through journalopenings (not shown) in wall portions 47, 48 of support member 17. Anend cap 49 is secured to an end of shaft 32 and supports a handle 46.Rotation of handle 46 causes rotation of shaft 32 and handle 46 isrotatable through an arc of approximately 180. A peripheral track 44 incam 31 mates with roller 53 and maintains alignment between push rodassembly 26 and cam 31 as cam 31 is manually rotated through thementioned are. Due to the compressive force outwardly exerted on plate55 by springs 45, roller 53 is always held against track 44. Thus, pushrod assembly 26 advances into and-withdraws from guide member 20according to the rotation of cam 31. As illustrated in FIG. 3, push rodassembly 26 is shown in an open position and cam 31 is shown rotated toan extreme outward position. In FIG. 4, push rod assembly 26 is shown ina closed" position and cam 31 is shown rotated to an extreme inwardposition.

Referring now to FIG. 5, there is shown at position A a so-called Beemcapsule. This type of capsule comprises a frusto-conically shapedpolyethylene thin walled shell or casing 70 which acts as a mold duringembedding. Casing 70 is adapted to receive an electron microscopy tissueparticle and a liquid polymer embedding medium which polymerizes aroundthe sample when subjected to appropriate environmental conditions,preparatory to being thinly sliced on a rotary ultramicrotome. Referringto FIG. 3, in order to separate the polymerized embedding material fromthe polyethylene capsule casing 70, the filled capsule is placed smallend first into aperture 11 of the invention apparatus 10, an operationanalogous to loading a cartridge into the open chamber of a bolt actionrifle. As shown in FIG. 4, push rod 50 includes a blunt tip portion 68which is slightly narrower than the inside diameter of casing 70 andwhich is adapted to abut against only the embedding or plastic blockportion 71 of the capsule. When handle 46 rotates cam 31 in a forwarddirection, push rod assembly 26 is advanced into guide member 20 andblunt tip 68 abuts with the now polymerized embedding portion or block71 and urges the capsule casing forward in the central cylindricalcavity 23 and between the laterally disposed blades 27, 28 so as toimpart longitudinal s lits 75 along both sides of the capsule casing 70.Due to the leverage afforded by the disposition of the large cam 31 withreference to roller 53 slitting of a typical capsule is now easilyaccomplished. FIG. 5 at position B, shows the capsule casing 70 afterhaving been slit longitudinally and manually parted alongslits 75 toexpose the polymerized block 70 and enables easy removal of the same.

An important feature to note is that at no time is the narrow tissuecontaining tip portion of the capsule subjected to tensive orcompressive forces as has been the case in the past. Thus, whilevirtually eliminating the changes of damaging the tissue sampleinvolved, or the possibility of accidental bodily injury as is commonwith conventional capsule slitting apparatus and methods, it is clearthat the apparatus of the present invention provides an extremely simpleand effective means for slitting electron microscopy tissue embeddingcapsules. It may also be noted that the blade edges are arranged toclear the tip portion of the push rod but to penetrate capsule to thedepth of the capsule casing so as to slit the casing on both sides butto minimize the opportunity for damage to the embedded tissue.

What is claimed is:

1. In an apparatus for slitting the outer casing of an electronmicroscopy tissue capsule of the type having a tissue particle embeddedin a plastic block having cylindrical shaped body and frusto-conicalshaped end portions with the block being encased in a casing ofcorresponding shape and with one end of said body portion exposed,comprising, in combination:

a. a base plate adapted to rest on a work surface;

b. a guide member rigidly supported on and above said base plate, saidguide member comprising a block having a horizontal and centrallypositioned open ended cylindrical bore extending within and throughoutthe length thereof and having an aperture formed in the top and adjacenta forward end of said block and communicating withsaid bore, saidaperture being shaped to accept placement of an electron microscopytissue capsule therethrough to rest in said bore in a loose slidablerelation therewith;

c. an elongated push rod member residing and slidable in said bore andhaving a tip portion movable from a first position rearwardly of saidaperture to a second forward position adjacent a forward end of saidbore, said tip portion being shaped to engage at said first position thesaid exposed cylindrical shaped capsule block end portion and to pushthe capsule forwardly to said second position;

d. a plurality of blades having cutting edges, said blades being fixedlypositioned in said guide member below said aperture and adjacent saidbore and with said edges being positioned clear of the path of movementof said tip portion 'but within said bore sufficient to engage and slitthe casing wall of said capsule when said capsule block end portion isforced by said tip portion from said first to said second position; and

e. an operator means mounted on said base plate for operating said pushrod member, said operator.

means including resilient spring means mounted to constantly urge saidpush rod rearwardly and said tip portion towards said first position andincluding a rotatable camming member having an operator handle adaptedwhen rotated in one direction to force said push rod member forwardlyand said tip portion to said second position to effect said slitting andwhen rotated in the opposite direction to allow said spring means tomove said tip portion to said first position preparatory to receivinganother capsule for slitting.

track in constant engagement.

1. In an apparatus for slitting the outer casing of an electronmicroscopy tissue capsule of the type having a tissue particle embeddedin a plastic block having cylindrical shaped body and frusto-conicalshaped end portions with the block being encased in a casing ofcorresponding shape and with one end of said body portion exposed,comprising, in combination: a. a base plate adapted to rest on a worksurface; b. a guide member rigidly supported on and above said baseplate, said guide member comprising a block having a horizontal andcentrally positioned open ended cylindrical bore extending within andthroughout the length thereof and having an aperture formed in the topand adjacent a forward end of said block and communicating with saidbore, said aperture being shaped to accept placement of an electronmicroscopy tissue capsule therethrough to rest in said bore in a looseslidable relation therewith; c. an elongated push rod member residingand slidable in said bore and having a tip portion movable from a firstposition rearwardly of said aperture to a second forward positionadjacent a forward end of said bore, said tip portion being shaped toengage at said first position the said exposed cylindrical shapedcapsule block end portion and to push the capsule forwardly to saidsecond position; d. a plurality of blades having cutting edges, saidblades being fixedly positioned in said guide member below said apertureand adjacent said bore and with said edges being positioned clear of thepath of movement of said tip portion but within said bore sufficient toengage and slit the casing wall of said capsule when said capsule blockend portion is forced by said tip portion from said first to said secondposition; and e. an operator means mounted on said base plate foroperating said push rod member, said operator means including resilientspring means mounted to constantly urge said push rod rearwardly andsaid tip portion towards said first position and including a rotatablecamming member having an operator handle adapted when rotated in onedirection to force said push rod member forwardly and said tip portionto said second position to effect said slitting and when rotated in theopposite direction to allow said spring means to move said tip portionto said first position preparatory to receiving another capsule forslitting.
 2. An apparatus as claimed in claim 1 wherein said operatormeans includes a roller member mounted on a rearward end of said pushrod member, said camming member includes a camming track engageable withsaid roller member and said resilient spring means is effective tomaintain said roller member and camming track in constant engagement.